1. Field of the Invention
This invention relates, generally, to oral splints. More specifically, it relates to the reduction and maintenance of reduction in mandible and/or maxilla fractures of edentulous or partially edentulous patients.
2. Brief Description of the Prior Art
Oral splints are commonly known in the art, including those utilized for fixation of the jaw during recovery from mandibular or maxillary fractures. For example, U.S. Pat. No. 6,227,861 to Cartledge et al. discusses a pre-formed mandible splint and a method of aligning and stabilizing a fractured mandible with such a splint. The splint approximates the curvature of the lower teeth or gingiva of the lower jaw. The splint is U-shaped, follows the human dentition, and has rows of holes or slots along its outer and inner perimeter. The splint is placed on the teeth and wired through the holes or slots to the mandible to align the mandible. Fractures are then to be screwed into place according to the curvature of the splint. Cartledge attempts to improve upon the art by eliminating the need of wiring the patient's jaw shut. However, the splint of Cartledge is pre-formed and is intended to uniformly fit the population, and thus is not contoured to each patient's anatomy, but rather provides a singular, uniform flat surface in contact with variable anatomy. As the splint is in a fixed, straight plane, the patient's teeth may not all be at the same height in order to make adequate contact with the splint. Inconsistent dental height between adjacent teeth is common, especially in partially edentulous patients. Partially edentulous patients often have gaps between teeth from missing teeth. Any areas of missing teeth can lead to lengthening of the opposing tooth, as it does not have proper occlusal contact. For example, if a mandibular lateral incisor is absent, the opposing maxillary dentition will lack normal occlusal contact, which can result in lengthening of the opposing maxillary tooth. This further adds to any height discrepancies between teeth and leads to areas of non-contact between the tooth and splint, ultimately causing fracture malreduction. As such, Cartledge fails to provide either equally distributed contact or stability of fracture reduction. Further, the splint of Cartledge does not address the occlusion of the patient. If the splint rests in contact with dentition, it interferes with proper occlusion, which is the primary objective in fracture reduction. If the splint rests in contact with the gingiva directly, as in the case of an edentulous patient, then the proper distance is not maintained for the patient to wear their denture appliance postoperatively. Also, the Cartledge device is designed only for tooth-bearing regions of the mandible, including fractures of the symphysis, parasymphysis, and body. The device does not assist in reduction of mandible fractures of the angle, ramus, condyle or coronoid.
Additionally, U.S. Pat. No. 6,671,539 to Gateno et al. describes a method of forming a surgical splint to receive a patient's dentition and align the upper jaw and the lower jaw during surgery. The method disclosed includes generating a computed tomography (CT) computer model of bone structure, generating a digital dental computer model of the patient's dentition, and combining the CT computer model and the digital dental computer model to form a composite computer model. The upper jaw and lower jaw are repositioned to form a “planned position” computer model. Thereafter, a computer model of the surgical splint is formed to direct fabrication of the splint. However, this methodology is quite complex and involves multiple steps, including separate dental trays, dental modeling, and merging of the facial bone CT with dental CT data. This can become very time-consuming and inefficient in the fabrication of the splint. This device also does not address fracture reduction but rather is for craniofacial and maxillofacial deformities requiring osteotomies, which is not used for fracture reduction. The device also does not address postoperative maintenance of the surgical splint. The device does not appear to be designed to remain in place postoperatively, but rather serves only as an intraoperative device.
U.S. Pat. No. 6,086,365 to Fields discusses fracture reduction and maxillary fixation by using a dental splint that is cemented directly to the patient's teeth to immobilize the patient's jaw during and following oral surgery. The splint includes an arch band having a back side that receives the bonding cement and a facial side from which multiple ligature studs project for engaging ligature wires. The arch band further includes flow passages that permit bonding cement deposited on the back side to flow onto the facial side as the arch band is pressed against the patient's teeth. However, this device is not personalized for individual patient and also requires bonding to the patients teeth. As it requires bonding to teeth, the device cannot be used in edentulous patients. Furthermore, the postoperative stability of the device is limited by the relative strength of the bonding agent used.
U.S. Patent Application Publication No. 2007/0074729 to Magnin describes a mandibular advancement splint used to treat snoring and sleep apnea. The splint is formed of two thermoformable trays designed to envelop the upper and lower arch. In order to adapt to individual variations in teeth, the splint includes an articulated frame having rigid and flexible elements, immersed in the thermoformable flexible material or molded around it. However, as indicated, the device is incapable of assisting with fracture reduction and is constructed of a thermoformable tray. This device is also only used while sleeping.
Metzger et al. (Marc Christian Metzger. Bettina Hohlweg-Majert, Uli Schwarz, Matthias Teschner, Beat Hammer, Rainer Schmelzeisen, Manufacturing splints for orthognathic surgery using a three-dimensional printer, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, Volume 105, Issue 2, February 2008, Pages e1-e7, ISSN 1079-2104) discusses the use of various tomographic techniques to produce a virtual rendering of a patient's jaw in order to produce splints for orthognathic surgery using a 3D printer. Data is acquired from the patient with orthognathic deformation via CT scan or cone beam computed tomography (CBCT) scan. The jaws are virtually repositioned and encoded, followed by printing of the splint. However, this device fabrication requires a separate dental scan or scanning of plaster dental models, the information of which is then incorporated into a facial bones CT scan. The device also addresses orthognathic surgical procedures, rather than reduction of maxillary or mandibular fractures and is incapable of performing as such. Further, the device utilizes intraoperative splints, but does not comment on the ability of the splint to remain postoperatively. The device can only be used in patients with dentition and thus cannot be applied to partially or completely edentulous patients.
Kocabay et al. (Ceyda Kocabay, Mustafa Sancar Ataç, Burak Öner, Nadir Güngör, The conservative treatment of pediatric mandibular fracture with prefabricated surgical splint: a case report, Dental Traumatology Volume 23, Issue 4, pages 247-250, August 2007) discusses the use of a pre-formed surgical splint for mandibular fracture fixation. This publication discusses the development of a custom, pre-formed splint for mandibular fracture fixation though the use of pressure molds. The device utilizes plaster dental modeling for formation of the acrylic splint, which can hinder the availability of the splint for operative use. The device further requires dentition to maintain fracture stability, and thus does not have application to partially or completely edentulous patients.
In the case described by Kocabay et al., the fracture was a midline symphyseal mandible fracture. In this type of fracture, the rotational forces are minimal. In all other types of mandibular fractures, the rotational forces acting to disrupt fracture alignment are much greater. As the device is depicted, it is unlikely the acrylic splint alone could maintain fracture reduction with these strong, additional rotation forces characteristic of mandibular fractures. The device is illustrated in a pediatric fracture, which is likely a greenstick fracture, as the authors acknowledge. This means that the periosteum overlying the fractured bone remains intact on at least one side. With intact periosteum from a greenstick fracture, reduction of the fracture becomes significantly easier than when the entire periosteum is disrupted and the fracture segments are freely mobile. In the adult patient, greenstick fractures are not seen, but rather, the entire periosteum is disrupted. Thus, in an adult fracture, it is doubtful that the acrylic splint would reduce the fracture and maintain postoperative alignment.
Generally, in difficult patient populations, such as those with edentulism or partial edentulism, there are very limited options for maxillomandibular fixation, and none provide stable reduction of fractures, including the foregoing devices and methodologies discussed. What is currently practiced in the art for an edentulous and partially edentulous patient with dentures, is that the patient's jaw is imaged upon removal of the dentures to ensure that the dentures are not blocking any visible fractures or other dentition. In many cases, the dentures are worn down and thus are not positioned where the patient's jaws should be aligned. As a result, the patient's jaw may have collapsed to an extent. To maintain the jaw in place then, the dentures are drilled or screwed into place since there is no other manner of estimating the spacing between the maxilla and mandible. This destroys the dentures for any future use and forces the patient to purchase a new set of expensive dentures.
Accordingly, what is needed is an improved reduction splint, and method of fabrication thereof, for edentulous and partially edentulous subjects or patients. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.
All referenced publications are incorporated herein by reference in their entireties. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.